Bimetallic element



Patented Sept. '13,-192 1 UNITED STATES wmuua '11.

CHACE, OI DETROIT, MICHIGAN, ASSIGNOR TO W. I. CHACE COMPANY, ACORPORATION OF MICHIGAN.

VALVE IBIHETALLIC ELEMIENT {Rom-swing. I

. lic element of high heat-resistant quality coupled with acomparatively high coeflicient of expansion welded into a nickel-steelelement of low coefficient of expansion.

I am aware of various compositions of metal used in bimetallic elementsfor instance brass and nickel-steel alloy and, while this element ispracticable up to tempera tures of about 4.50 degrees F., it becomesimpracticable for use with higher temperatures. It is also necessary inapractical device for use under higher temperatures'to provide a metalhaving a coefiicient of expansion approximately equal to that of brassto secure an element readily -.responsive to temperature change. Theelement made of the two metals hereinafter described has this quality ofready responsiveness to temperature change-except that it is slow to ex-,pand under temperatures below 200 degrees F., and is more readilyresponsive to higher degrees of temperatures. object of the invention tosecure an element that is practically non-responsive or at least slow inresponsiveness to temperatures below 200 degrees F. The bimetallicelement herein described is useful wherever the element is subject tohigh temperatures as in making or'breaking the electric circuit in anelectric hand iron or in the controlling of the valve in oil refiningsystems for internal combustion engines and various other places andmayhave any desired form either as a disk as is used in the electrichand iron or as an elongated strip asis used in an ordinary thermostat.depending upon the character of the apparatus with which it is used andthe function it is to perform. With the electric hand iron the brass andiron bimetallic element is-practically useless due to the fact thatthebrass loses its elasticity at about 450 degrees E, which I have termedits critical temperature. This term as hereinafter used refers to thepoint beyond which the bimetallic element would become unreliable. Witha structure in which brass forms one of the elements therefore it isimpossible to utilize the same under temperature in excess of 450degrees F., and in the electric hand iron the temperature thereof in useis approximately 600'degrees F.

For this purpos e sometimes metal'known as Monel metal has been used asone of the This also is an Application filed July 6, 1925. Serial in.41,887.

elements in conjunction with the nickel-steel I alloy. The criticaltemperature of Monel metal, however,- is about 600 degrees F., andtherefore it is not of. long life when used with an electric hand ironor other device wherein it is subject to such a temperature andfurthermore requires too great a temperature change to cause movement ofthe element to the necessary extent.

One of the features of my improved bimetallic element is that itscritical temperature is about 1200 degrees F., and is therefore useful.in a great many places where previous elements of another type of metalis impracticable or not of long life.

My improved bimetallic element consists of :a nickel-steel alloy inwhich the nickel content is from 36 to 42 per cent andwhich has a lowcoeflicient of expansion and the other element which I have utilized hasa coeificient of expansion approximately equal to that of brassnamely,about .070 inches per foot.

Preferably my composition consists of Per cent. Carbon .50 Manganese .70Silicon 1.75- Chromium -n 8.00 Nickel 22.00 Copper 2.00 Cobalt 1.00 Iron64.05

In making my bimetallic element I Weld a bar of nickel-steel alloy and abar of the 'above compositiontogether and roll the same to the desiredthinness. From this sheet is cut the. element in the desired form eithera disk or other shape as may be desired and 95 depending upon thepurpose for which it is to be used. This is the usual practice in themaking of a bimetallic element. With my bimetallic element one member ofwhich has a high coeificientofexpansion formed of approximately thecomposition above stated and the other member of nickel-steel alloy Isecure a bimetallic element as eflicient at high temperatures as is theusual brass such temperature, and further one that is .very slow toexpand at temperatues below 200 degrees F. My new element attemperatures above 200 degrees F., is readily responsive to heat and isperfectly adapted for use in such places as in controllin circuits in anelectric hand iron due to rapi responsiveness to temperatures around 600de rees F., and which is affected readily by sight changes intemperature. In the usualMonel metal and steel alloy heretofore usedwith an electric hand iron a change of approximately 10 de rees intemperature is required to effect ma ring and breaking of circuit. Withmy composition the metal is responsive and will make and break thecircuit within a range oi about 5 degrees F., it having a criticaltemperature of about 1200 degrees makes it very efiicient for use withthe electric hand iron and in other places where the element issubjected to temperature up to 1200 degrees F., and without lo s of itselasticity.

A bimetallic element of the composition herein described will actapproximately with equal rapidity to the previous brass and nickel-steelelements or nickel-steel and Monel metal above mentioned and when usedwith an electric circuit in the form of a disk the flexing of the diskis so rapid under variations in temperature than in breaking of thecircuit no arcing occurs at the contacts.

I am aware of various compositions of metal used in bimetallic elements,and my invention consists not so much in the composition used as it doesin the production of a bimetallic element characterized by its heatresistant quality and rapid expansion under temperatures above 200degrees F., and its slowness to expand under temperatures below 200degrees F., combined with a metal of much lower coefiicient of expansionhaving a high percentage of nickel. The two elements welded togetherform a bimetallic element having the stated qualitiesnamely, high heatresistant quality withstanding temperatures of practically 1200 degreesF., without impairing the clasticity of the element of high coefficientof expansion, is slow to respond to temperatures below 200 degrees F.,and above such temperatures expands and contracts as readily as theusual brass and steel elements.

Having thus described my invention what I claim and desire to secure byLetters Paient of the United States is-- 1. A bimetallic elementcomprising two nemesis metal elements fused together, each of saidelements retaining its elasticit at tem era tures as high as 1200degrees one 0 said elements containing approximately forty per centnickel and characterized'by havin a low coeiiicient of expansion, andthe ot er of said elements being of a composition in which ironpredominates and characterized by its havin a coeflicient of expansionof approximate y .070.at temperatures above two hundred degrees F.

2. A bimetallic element having as one of the said elements anickel-steel alloy in which the nickel content is not greater thanfortytwo per cent to which is welded a steel containing approximatelythe following compo sition- Carbon 3. A bimetallic element having as oneof its members a metal approximately of the following composition-Carbon .50 Manganese .70 Silicon 1.75

' Chromium 8.00 Nickel 22.00 Copper 2.00 Cobalt 1. 00 Iron 64.05

and as the other member a metal oi a lower coefficient of expansion.

4. A bimetallic element consisting of two elements fused together. oneof the elements being nickel steel alloy characterized by having a lowcoellicient of expansion and the other being of a composition of metalsin which iron predominates and characterized by having a materiallyhigher coeilicient of expansion and capable of retaining, its e1asticityat a temperature as high as twelve hundred degrees F., and being mostrapidly expandible through a working range of from five hundred to sevenhundred degrees F.

In testimony whereof, l sign this specitication.

WILLIAM M. canon.

